Clustering: Initiate snapshot interferes with fake snapshot

During initiate snapshot (when being sent to follower), we do not set the captureSnapshotInitiated flag to true.

Fake snapshot can kick in and mess up the indices.

Also Initiatesnapshot should resemble the fake snapshot as for a slower follower the leader would keep sending snapshot after a real one.

For a leader we can do a real snapshot based on the replicatedToAllIndex and not the last applied. This means that in a stable system, there would be less snapshot sent and more in-mem log entries

For a follower, the real snapshot should follow the replicatedToAllIndex sent via Leader's AppendEntries